Hypertension is more prevalent, starts at an earlier age, tends to be more severe and more frequently remains undiagnosed and untreated in African Americans compared to white Americans. Previous studies indicate that high levels of psychosocial and environmental stress contribute to these disproportionate rates of hypertension in this minority population. Proposed mechanisms for this effect include excess sympathetic nervous system activation and cardiovascular reactivity. Previous randomized controlled trials in African American populations with high blood pressure conducted by the Center team have demonstrated that stress reduction intervention with the Transcendental Meditation (TM) program is associated with reduced blood pressure levels compared to health education control (HE) intervention over short and long-term follow-up periods. This effect may contribute to reduced cardiovascular morbidity and mortality rates observed in clinical trials with African Americans using meditation. However, there is a paucity of data on the physiological mechanisms for this clinical effect. Therefore, the overall objective of this study is to investigate acute and chronic effects of meditation on cardiovascular and autonomic nervous system mechanisms of high blood pressure in this high-risk minority population. This will be a randomized controlled mechanistic trial of 152 hypertensive African American adults 40 years and older who will be allocated to either the TM program or a HE control group for three months. The experimental protocol will test for clinic BP, ambulatory BP, and chronic and acute physiological responses to stress in the laboratory. Acute lab stressors will include mental arithmetic, cold pressor and exercise treadmill. Specifically, we will assess cardiovascular and plasma catecholamine reactivity to lab stressors;hemodynamic responses, comprising heart rate, blood pressure, stroke volume, cardiac output, and total peripheral resistance;arterial compliance, and cardiac autonomic nervous system tone using heart rate variability. Laboratory blood pressure patterns will be compared with ambulatory blood pressure monitoring in the naturalistic environment. Possible mediators through which the intervention affects blood pressure (i.e., psychosocial factors, behavioral factors, autonomic tone, CV reactivity and hemodynamic factors) will be investigated standard mediator analyses for intervening variable effects with regression models. The results of this study will provide much needed data on cardiovascular, neuroendocrine, autonomic and behavioral mechanisms by which a stress reduction intervention may lower blood pressure and thereby prevent and treat hypertension in this African American population. The application has several strengths including the expertise of the investigative team, previous extension of the investigator's prior work, a "translational" approach to understanding the underlying biological, behavioral, and psychosocial factors involved, use of measures which are theoretically strong, the randomized controlled study design, and the high likelihood that the study will be successfully completed. However, there are several minor study design issues that all appear remediable. Overall enthusiasm for this application remains high.